2. Equipment: welding unit

Electric generator

MIG/MAG welding uses direct current. The positive pole is at the electrode (DCEP polarity). MIG/MAG welding generators are said to have a horizontal or constant voltage characteristic. This property is important in explaining the semi-automatic nature of the process. In arc welding, arc height is linked to voltage: an increase in the gap between cathode and anode generates an increase in voltage, and vice versa. Figure 2 shows two arc characteristics associated with a MIG/MAG generator. Their intersections represent the operating points. It can be seen that a small change in arc voltage (or arc height Δh ) in turn generates a large change in current ΔI. This parameter is linked to the unwinding speed. Thus, the unwinding speed will increase...